Agree with others that the Push is good; I have a Push 2 that I love. It's great for chords and melodies because the layout is massive (8x8). However, it's somewhat expensive (the 2, anyway) and the pads themselves could be better in terms of expressiveness/sensitivity. Also, it's only worth getting a Push if you have Ableton; as a controller for Ableton it really shines.
If you want really expressive pads, which foster dynamics and also allow you to do things like finger drumming (I really recommend questforgroove.com if that sounds interesting to you), the best pad controllers are the ones in the Maschine line-up, by Native Instruments. I have an MK3 but the more basic versions are also apparently very good. The layout is much smaller (4x4) but the pads are massive and super sensitive, they are a joy to play.
A lot of people also use Launch pads by Novation, I don't know much about them, but they are quite popular and they are, I believe, on the cheaper side. https://novationmusic.com/en/launch
Rumour has it that a Push 3 is not too far away, so keep that in mind when considering the Push lineup from Ableton.